Comparative Efficacy of Intraoperative Patient State Index vs. Bi-Spectral Index in Patients Undergoing Elective Spine Surgery with Neuromonitoring Under General Anaesthesia: A Randomized Controlled Trial

Objective: Various electroencephalogram-based monitors have been introduced to objectively quantify anaesthesia depth. However, limited data are available on their comparative clinical efficacy in various surgical procedures. Therefore, we planned this study to compare the relative efficacy of patient state index (PSI) vs. Bi-spectral index (BIS) assessment in patients undergoing elective spine surgery under general anaesthesia. Methods: This prospective, parallel-group, single-center study included patients undergoing major spine surgery with neuromonitoring. Patients were randomized into two groups, i.e., group B (undergoing surgery under BIS monitoring) and group P (undergoing surgery under PSI monitoring). The primary objective was to compare the time to eye opening after stopping anaesthetic drug infusions. Results: The mean propofol dose required for induction in group B was 130.45 +/- 26.579, whereas that in group P, it was 139.28 +/- 17.86 (P value 0.085). The maintenance doses of propofol and fentanyl required for surgery were also comparable between the groups. Time to eye opening was 12.2 +/- 4.973 in group B and 12.93 +/- 4.19 in group P, with a P value of 0.2664 (U-statistic-684.50). Conclusion: The intraoperative PSI and BIS had similar clinical efficacy in terms of the dose of propofol required for induction, time of induction, maintenance dose of propofol and fentanyl, time of eye opening, and recovery profile in patients undergoing elective spine surgery under neuromonitoring.